No pictures available
Lactic acid bacteria are found in many foods, for example, yoghurt, cheese or sauerkraut. These bacteria are desirable, as they change the taste and consistency of a raw material in such a way that a completely new foodstuff is created. In the manufacture of cheese, propionic acid bacteria also play an important role. They are responsible for the holes and the special taste of Emmental cheese. In a project of the Swiss National Science Foundation, researchers at the Laboratory of Food Biotechnology of ETH Zurich have discovered that these two groups of bacteria have other very useful properties.
In extensive studies, researchers at ETH have isolated over 1000 different bacteria from foodstuffs. They found 80 strains of lactic acid bacteria and ten strains of propionic acid bacteria that inhibited the growth of yeasts and moulds in yoghurt containing fresh fruit. A specific combination of lactic acid bacteria and propionic acid bacteria proved to be particularly effective. This culture extended the shelf-life of artificially contaminated yoghurt by more than two weeks.
To be sure that the bacteria chosen are safe, harmless strains, researchers at ETH have accurately characterised and identified them. For this, they carried out microscopic investigations and biochemical tests. Additional detailed molecular biological investigations then enabled a very accurate and reliable identi-fication to be made.
Out of the originally large number of bacterial strains, a combination of two strains has recently successfully reached the market. It is now being sold as a protective culture. The work of ETH researchers on this is not yet at an end. In a follow-up project, they are working together with industry to investigate why this protective culture is so effective against yeasts and moulds. The first products of metabolism from the culture have already been isolated, but the precise mechanism and the interaction between the two strains is still an exciting mystery that ETH researchers want to solve.Reference: Miescher Schwenninger, S., L. Meile 2004. A mixed culture of Propionibacterium jensenii and Lactobacillus paracasei subsp. paracasei inhibits food spoilage yeasts. System. Appl. Microbiol. 27: 229-237. The article is to be found under http://www.sciencedirect.com/science/journal/07232020>
Diese Website wird in älteren Versionen von Netscape ohne graphische Elemente dargestellt. Die Funktionalität der Website ist aber trotzdem gewährleistet. Wenn Sie diese Website regelmässig benutzen, empfehlen wir Ihnen, auf Ihrem Computer einen aktuellen Browser zu installieren. Weitere Informationen finden Sie auf
The content in this site is accessible to any browser or Internet device, however, some graphics will display correctly only in the newer versions of Netscape. To get the most out of our site we suggest you upgrade to a newer browser.